System eor the transmission and reception of radiant energy



Nov. 16, 1926. 1,607,158

J. H. HAMMOND. JR

SYSTEM FOR THE TRANSMISSION 'AND RECEPTION OF RADIANT ENERGY Original Filed Feb. 15. 1918 9 Sheets-Sheet 1 520 521 524 Emwtoz JOHN HAYS'HAMMGND JR.

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SYSTEM FOR THE TRANSMISS ION AND RECEPTION OF RADIANT ENERGY Original Filed Feb. 15. 1918 9 Sheets-Sheet 5 I llllllllllllllllisso an uamtoz JOHN HAYS HAMMOND JR.

NOV. as, 1926. 1,6215% J. H. HAMMOND. JR

SYSTEM FOR THE TRANSMISSION AND RECEPTION OF RADIANT ENERGY Original Fi 15 1918 9 Sheets-Sheet 6 'i l l auventoz JOHN HAYS HAMMOND JR.

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SYSTEM FOR THE TRANSMISSION AND RECEPTION OF RADIANT ENERGY Original Filed Feb. 15. 1918 9 s t -sh t 7 sag gwucutoz JOHN HAYS HAMMGND JR. 333% hi a'fl'to wveq Nov. 16 1926. 11,6Q7J58 J. H. HAMMOND. JR

SYSTEM FOR THE TRANSMISSION AND RECEPTION OF RADIANT ENERGY nal Filed 1918 9 Sheets-Sheet 8 119 m Bill! l l i i l l lt JOHN HAYS HAMMOND JR.

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SYSTEM FOR THE TRANSMISSION AND RECEPTION OF RADIANT ENERGY ori inal Filed Feb. 15 1918 9 Sheets-wh JOHN HAYS HAMMOND JR.

Patented Nov. 1%, i926.

J'tYHlbl' HAYS HAMMOND, JB., OF GLOUCESTER, MAFSSACHUSETTS.

Original application filed February 15, 1918, Serial No. 217,425.

598,208. Patent No. 1,463,994, dated August 7, 1923.

Renewed October 31, 1922, Serial No. Divided and this application filed August 2,

1923, Serial No. 655,214. Renewed March 27, 1926.

This application being a division of myapplication Ser. No. 598,208, filed October proved receiving system for radiant ener y;

to provide an improved method for the transmission of radiant energy; to provide an improved system. for the transmission of radiant energy whereby secrecy of operation may be maintained and interference may be avoided; and to provide a selective system for the transmission of radiant energy wherein a plurality of wave trains or series of waves are simultaneously emitted in such a manner that there will be a predetermined difference in phase relationship between different series or trains of waves, and wherein the plurality of series or trains of waves are selectively received by a receiving system in such amanner that a receiving device, forming part of the receiving system, is caused to operate only as a result 01": the. predetermined difference in phase of the received waves.

In the accompanying drawings, all of which are diagrammatic views of systems constructed in accordance with this invention, Figs. 1 and 2 are views respectively of two diiterent forms of transmission systems; Figs. 3 and 4 are views respectively of two different forms of receiving systems, either of which is adapted to be used in connection with either of the forms of transmission systems shown in Figs. 1 and 2; 5 is view of a modified form of transmission system; F ig. 6 is a view of a further modified form of transmission system; Fig. 7is a view of a receiving system adapted to be used in connection with the transmission system shown in Fig. 6; Fig. 8 is a view of a further modified form of transmission system; Fig. 9 is a view of a receiving sys tem adapted to be used in connection with the transmission system shown in Fig. 8; Fig. 10 is a view of a modified form of reiteiving system; and 11 is a view of a further modified form of receiving system.

Referring to the drawings and particu larly to Fig. 1, one form of transmission system constructed in accordance with this invention comprises two open aerial circuits and 30, arranged to emit respectively two series or trains or high frequency oscillations of different frequencies respectively, for instance, of 300,000 per second and 250,000 per second, respectively. These two aerial circuits 25 and include respectively an antenna 31, grounded as at 32 through an inductance 33, and an antenna 34, grounded as at 35' through an inductance 36. The two inductances 33 and 36 form the secondaries of two transformers 40 and 41, which include respectively two primary coils or inductances 42 Land 43, which are arranged respectively in the two closed os cillatory circuits 44 and 45, which include respectively two spark gap devices 46 and and two variable condensers 48 and 49. These two closed oscillatory circuits 44 and are adjusted in a well-known manner in relation to their respective open aerial circuits 25 and 30 to causetheopen aerial circuits 25 and 30 to be effectively stimulated by them. The two variable condensers 48 and 49 are arranged to be charged from any suitable source of direct current of high voltage, as, for instance, from a direct cur-' rent generator 50 giving a potential of about 500 volts, one brush 51 of this generator being connected through a rheostat 52, choke coil 53 and conductor 54 to. one side of the variable. condenser 48, and through a branch conductor 55. choke coil 56 and conductor 57 to one side of the variable condenser 49. The other brush 58 of the generator 50 is connected through a conductor 59, choke coil 60 and conductor 61 to the other side of the variable condenser 48, and through a rheostat 65, choke coil 66 and conductor 67 to the other side of the variable condenser 49. r a

For simultaneously impressing upon the two series of high frequency waves of oscillations emitted by the open aerial circuits 25 and 30, respectively, two series of periodic amplitude variations having the same frequencies respectively, for'instance, of 20,000 per second, two secondary frequency imposing devices or tone circuits comprising respectively inductance 75 and a variable condenser 76 in seriestherewith, and an inductance 77 and a variable condenser 78 in series therewith are shunted respectively about the two variable condensers 4.8 and 49.

For producing a predetermined phase relationship between the two series of periodic amplitude variations, the two tone circuits 75, 76 and 77, 78 are operatively connected by an intermediate circuit 100, which includes two coils-101 and 102, and a primary variable condenser 103. Shunted around" the primary condenser 103 is a seccondary va iable condenser 104-, which is providedwith a key 105 whereby the condenser 104: will be thrown into operation. The two coils 101 and 102 are inductively connected respectively to the two coils and iary circuit 11, including a coil 112 and a telephone transmitter or microphone 115 may be" arranged so that the coil 112 of the auxiliary circuit will be acted-upon inductively by and will react. inductively upon the: coil 110 of the intermediate circuit 100, In this arrangement when'the switch 105 is closed and the operator speaks into the-telephone transmitter 115,.the interaction between the two tone circuits 7 5, 7 6- and 77-, 78 through the intermediate circuit 100 will be modified in such a manner that the phase difference between the two series. of pe-- riodic amplitude variations of the system will be varied in accordance with the sound waves received by the telephone transmitter 115. I V v In the operation of the transmission systemshown in Fig. 1, with the switch 105 closed and the generator 50 in operation, the two open aerial circuits 25 and 30will be caused to emit two continuous series of electro-radiant waves having wave frequeucies of, for instance, 300,000 and 250,000per second respectively. The amplitude of each (:f-illlGSG series-0t waves will be periodically varied in a uniform manner and at a predetermined frequency, the frequency of these periodic modifications in amplitude being the same, in both series of waves emitted, and as a result of the interaction between the two tone circuits 75, 7 6 and 7 7 7 8 and the intermediate circuit 100, the difference in phase between these two periodic modifications will be, for instance, substan tiallv Va -hen the switch. 105.- is open, the variable condenser 104C will. be cut out of operation and consequently the interaction between the two tone circuits 75, 7 6 and 77, 78 through the intermediate circuit will be varied and will decrease the phase difference between the two series of periodic ai'i'iplitude variations from 90 to 0, so that the two series of amplitude variations-will be in the'same phase. These two series of emitted waves thus periodically modified in amplitude maybe selectively received upon any suitable receiving system, as will be hereinafter described.

The modifiedtran'sniissicm; system shown in Fig 2 comprises a main open aerial circuit- 200 and an auxiliaryopen aerial circuit 201,. which include respectively an an tenna 208' grounded as at 20 k through a coil or inductance 205, and an antenna;- 206 grounded as at- 207 through a coil'210. The two open-aerial circuits 200 and 201 are arranged to be energized respectively by two high potential batteries 215 and-216, or

other suitable seurce ofhigh potential di: rect current, which are arranged-to act respectively through two. electrionic or-thermionic valves 217 and 218, which'a-re in series respectively with the two batteries 215- and 216, and inshunt circuits co n trolled respectively by switches 2-15 and.

21-6arou-nd the two coils 205-and-210-of the two open circuits 200 and 20-1 respectively. Each oitliese valves 21'? and, 218- comprises an evacuated glass bulb, or other suitable container, 220, in which-is-arranged a plateelectrode 221, agrid 222-, and a: filament 223, which is arranged to be heated bya battery 224i acting through a rheostat- 225. The two grids 222-, 222- are connected to their respective open circuits by two corresponding circuits includingrespectively two in-di'ictai'ices 22-5 and 226,- and two auxiliary coils 227 and 228. The coil 22? is inductively and adjustably coupled 'tothe coil 205, and the coil-228 is inductively and adjustably coupled to the coil-210. Shunted around the two induc inces 225 and 225 at difi'erent frequencies, 300,000 and 250,000oscillations and 201 are tunedto oscillate for This closed circuit 25% is a For impressing upon the two series of high frequency oscillations emitted by the two open circuits 200 and 201, respectivlv two series of periodic amplitude variation having the same "frequency, for instance, of 20,000 variations per second, an aut tiliary thermionic valve 24l0, of any well-known or suitable construction, is provided. In the formshown, this auxiliary valve 24:0 ineludes an evacuated glass bulb 241, or other suitable container, in which is arranged a plate electrod 242. a grid 24:3, and a lilament 2" The filament 2% is arranged to be heated by a battery acting; tl'irough a rheostat The auxiliary valve in a circuit controlled by a switch 240 and including a high potential battery 250, or other source of high potential, a main in-- ductancc 251, and an auxiliary inouctance A variable condenser 253 is unted around these two inductances 251 and and is thus arranged in a closed auxiliary circuit 254 containing these inductance es. ted so that its own free period of OSCl lation will be equal to the period of amplitude variations which it is desired to impress upon the emitted high frequency wave. The auxiliary inductance of his closed circuit is arranged to act inductively upon the main inductance 26 of the thermionic valve 218, which is connected to the auxiliary circuit 201. Ehe grid is in a circuit including coil 25%, which is inductively coupled to the main inductance 251 to'be reacted upon by the current in the auxiliary circuit 25 'l he thermioi'lic valve 24:0 is inductively connected with the thermionic valve which controls the main open circuit 200, bymean; of a closed oscillatory circuit 255, which contains a variable condenser 2.56, a main inductance 257, and a secondary inductance A variable condenser 260 is arranged to he shunted around the variable condenser 256and is controlled by a switch 261 which. is arranged to control the variable condenser 260 and which allows operation at the will of an operator. The noun inductance of the intermediate circuit 25' inductively coupled to the main indiu ancc ol' the circuit or aux'i valve iii-0, and. the secon ductanc of the ntermecluue c cu is inductively coup id to the indr e i ot'the tl'iermionic valve 21'? r' the main open circuit 200. the variable condenser 256 oi the intermediate circuit 255 may be :uljusted to give a desired phase relation betwcen the s ries ol periodic amplitiujle variations emitted by he main open circuit 200 and the series of periodic amplitude variations emitted by the secondary circuit 201. The arrangement is such that when the switch 261 is-closed, the variable condenser 256 may be adjusted to produce a comprises a. divided open n.

phase difference, for instance. of 90 htveen these two series of periodic amplitude variations.

To adapt the transmission system shown in Fig. 2 to be used for transmitting telephonic messages, a coil 262 may be included in the intermediate circuit 255 and an auxiliary circuit 263 including a coil 264: and a telephone transmitter or microphone 265 may be arranged so that the coil 26% of the auxiliary circuit 263 will be acted upon inductively by and will react inductively upon the coil 262 of the intermediate circuit in this arrangement, when the switch 261 is closed and the operator speaksinto the telephone transmitter 265, the operation of the intermediate circuit 255 will he modified in such a manner that the phase difference beween the two series of periodic amplitude variations of the system will be varied in accordance with the sound waves received by the telephone transn'iitter 265.

In the operation of the transmission sys tem shown in 2, when the switches 215, 216, 2 19 and 261 are closed, the two open aerial circuits 200 and 201 will be caused to emit two continuous series of electro-radiant waves having frequencies of, for instance 300,000 and 250,000 per second respectively, and periodic variations in the amplitude of these two series of waves will be effected as a result of the operation of the auxiliary valve 240 acting through the auxiliary circuit 25% and through the intermediate circuit 255, the frequency of these amplitude variations being the same in both series of waves, for instance 20,000 variations per second. These two series of amplitude variations will have a diiterence in phase or, for instance, 90, depending upon the adjustment of the variable condenser 256. l hen the switch 261 is open, this phase difference will be modified to such an extent as to render the systeni ineffective, as will appear hereinafter.

InFig. 3 is shownone form of receiving:

system constructed in accordance with this invention which 'may be utilized to receive waves transmitted from either of the transmission systemsshown in Figsv l and 2, or from any other similar or suitable transmission system, This form otreceiving system receiving circuit 275, including an antenna 276 which grounded as at 277 through two branch circuits, including respectively two variable condensers 278 andv279 and two coils 280 and 281. The circuit comprising the coudenser 278 and coil 280 is tuned to one of the high frequencies of the ti'ai iission system, for instance, to 300,000 oscillations per second, while the circuit comprising the anenna 276 and the other condenser 279 and the corresponding coil 281 is tuned to the 4 system, for instance, to, 250,000 oscillations per second. The two coils 280 and 281 form the primaries of two transformers 283 and 284, having secondary coils 285 and 286,

which are in closed oscillatory circuits 287 and 288 which are tuned respectively to the two high frequencies of the open receiving circuits, for instance, 300,000 per second and 250 000'per second, and which are arranged to control two detectors 290 and 291 of any well-known and suitable construction, for instance, as-in the form shown, two gaseous detectors of well-known construction. These two detectors 290 and 291 are arranged. to

control two circuits 292 and 293, which include respectively two sources of high potential direct current, as, for instance, two high potential. batteries and 295, and two primary coils 296 and 297, which are arranged so that their longitudinal axes lie in the same plane and intersect at right angles. Each of these two primary coils 296 and 297 is arran ed in two aligned spaced sections and 297'and in a plane therewith are eight sec ondary coils 310, which are arranged in series to radiate substantially from the point of intersection of the axes of the two pri mary coils 296 and 297. These secondary coils 310 are spaced equi-angularly around their center of radiation so that the longi tudinal axes 01. the two primary coils 296 and 297 will respectively bisect the angles formed between corresponding consecutive secondary coils, as shown in the drawings.

The two pairs of primary coils 296 and i 297 correspond to the stator of a 2 phase induction motor, whose wound rotor is made up of windings 310. If only one phase is excited, as would be the case it detector 290 was responding to an interfering signal, an alternating magnetic field is set up between the two halves of coil 296. This'field cuts four of the coils of the rotor 310, which are connected at their inner ends, so that the resulting induced E. M. l3.s cancel each adjacent pair of rotor coils, thus leaving detector 315 unaffected. The same is true of an incoming interfering signal received by detector 291. and a similar result would be produced it both detectors290 and 291 were simultaneously subjected to an interfering signal. However, if a signal is received from one of the above described transmitters, are capable of emitting waves whose phase difference is 90, the two magnetic fields set up between the halves of coils 296 and 297 will differ in phase by 90, the result being, the well known rotating magnetic field of, say, the induction motor.

The action of this rotating field upon the secondary, or rotor coils 310, can best be understood by ii'i'iagining the field coils 296 and 297 to actually rotate in the plane of the paper. Suppose these be rotated 90. The magnetic field between the halves of any pair of coils, say coils 296, will now out four different rotor coils, each pair of which are connected together at their outer ends, and in such a manner that the induced E. M. F.s add. as mentioned above, in rotor coils connected together at their inner ends, the induced E. M. F.s oppose. Thus a voltage will be generated in rotor 310 by the alternating field, when displaced from the position shown in the drawing (Fig. 3). Instead of actually moving the field coils 296 and 297, their resultant magnetic field revolves,

inducing thereby a voltage in coils 310 of the same frequency, as that, supplied to the field coils 296 and 297. The secondary coils 310 are in a closed oscillatory circuit 311. which includes a variable condenser 312 and which is tuned to the secondary frequency of the system multiplied by the number of coils, for instance, to 160,000 oscillations per second. This closed circuit 311-is arranged to control a gaseous detector 315, or any other suitable detector, through an inter- It is to be remembered, that,

rupter 319. A shunt circuit 320, controlled by a switch 321, is provided around the interrupter 319 to render the interrupter either effective or non-efiective at the willof the operator. The gaseous detector 315 is arranged to control a circuit 323-including a high potential battery 32 i, or other source'ot current, a telephone 325, or a re lay, or any other well-known or suitable rcceiving instrument.

In the operation of the receiving system and 250,000 per second respectively in the two control circuits 292 and 293 and a secondary frequency of 20,000 per second in both these circuits. be a phase difference of substantially 90 in the periodic modifications of the two series of received waves, two series of electrical oscillations having substantially the It, now, there should 7 same frequency and intensity but having a difference in phase of substantially will be set up in the two coils 296 and 297. The result or the magnetic field of these two coils will be constant in strength'and will rotate uniformly, making one complete revolution for each cycle of the secondary frequency of 20,000 per second. This rotating magnetic field will induce in the closed oscillatory circuit 311 containing the secondary coils 310 electrical oscillations having a frequency equal to the secondary frequency of the system. This oscillation of the closed circuit 311 will cause the operation of the detector 315 which will cause unidirectional impulses having a frequency of 20,000 per second.

When the receiving system shown in Fig. 3 is used to receive telegraphic signals, the switch 321 is left open to render the interrupter 319 effective and the interrupter is rotated at a constant rate to interrupt the circuit at, for instance, 1,000 interruptions per second, so that when the current impulses are set up in the controlled circuit 323, these impulses will be interrupted at the rate of 1,000 interruptions per second and the telephone 325 will be caused to emit a tone having 1,000 vibrations per second, and which will be audible.

When the system shown in Fig. 3 is used to receive telephonic messages, the switch 321 is closed to render the interrupter 319 inef ective, and the controlled circuit 323 will then remain unbroken, and the telephone receiver 325 will be caused to emit sound waves as a result of and corresponding to the variations of the phase difference between the'two series of amplitude variations of the waves received by the system.

When a relay or other similar instrument is substituted in Fig. 3 for the telephone receiver 325, the switch 321 is kept closed, and when a wireless signal is being received unidirectional impulses will be set up in the circuit 323 as hereinbefore described, and as a result of these impulses the relay, or other similar instrument, will be operated.

In the case of static shocks or impulses acting upon the open aerial circuit 27 5 of the receiving system shown in Fig. 3, both of the controlled circuits 292 and 293, if affected, would be affected simultaneously, and hence could cause the circuits to oscillate, if at all, in the same phase. If currents of the same phase and intensity should pass through the coils 296 and 297, the resultant magnetic field would not rotate butwould remain fixed midway between the aXes of the two coils, and oscillations will not be set up in the closed circuit 311, and consequently the detector 315 and the controlled receiving instrument 325 will be practically u n a fi ec te d.

In 1 is shown a modified form of receiving system arranged to operate with either of the transmission systems shown in Figs. 1 and 2, or with any other suitable transmission system. This modified form comprises a divided open aerial circuit 350 constructed as hereinbefore described and comprising an antenna 351 which is grounded as at through two branch circuits including respectively two variable condensers 353 and 354, and two coils 355 and 356. The circuit through the antenna 351, condenser and coil 355 is tuned to one of the high frequences of the received waves, and the circuit through the antenna 351, condenser 354: and coil 356 is tuned to the other high frequency of the received waves. The coils 355 and 356 are inductively coupled respectively to two secondary coils 3571 and 357, which are arranged respectively in two closed oscillatory circuits 358 and 359, which are tuned respectively to the corresponding circuits of the primary coils 355 and. 356. These two closed circuits 358 and 359 are arranged to control two detectors 360 and 361 of any wellknown or suitable construction, for instance, two gaseous detectors of well-known construction, which are arranged to control two circuits 362 and 362 containing respectively two coils 364 and 364 and two high potential batteries 365 and 365, or other suitable sources of high potential. The two coils 3641 and 364 are arranged in two closed oscillatory circuits 366 and 367, which include respectively two variable condensers 368 and 368. These two closed circuits 366 and 367 are tuned to the secondary frequency of the received waves, for instance, to 20,000 oscillations per second, and are inductively coupled to two closed oscillatory circuits 369, and 369, which are tuned to the secondary frequency of the received waves, for instance, to 20,000 oscillations per second, and which are arranged to control two secondary detectors 370 and 371. The two secondary detectors 370 and 371 may be of any well-known or suitable construction, and in the form shown are gaseous detectors of well-known construct-ion. These secondary detectors are arranged to control two circuits 372 and 372, which include respectively two primary coils 373 and 374, and two high potential batteries 375 and 37 5. The primary coils 373 and 3741 are respectively in two closed oscillatory circuits 376 and 377, which include respectively two variable'condensers 378 and 378. The two coils 373 and 3741 are arranged so that their longitudinal axes lie in the same. plane and intersect at right angles, and each of these coils is in the form of two aligned spa'ed sections. Surrounded by the coil sections of the two primary coils 373 and 374 and in a plane therewith are eight secondary coils 380 which are arranged to radiate substantially from the point of intersection of the axes of the two primary coils 373v and 374:. These secondary coils 880 are spaced equi-angularly around their center of radiation, so that the longitudinal axes of the two primary coils 373 and 374 will respectively bisect the angles formed between corresponding consecutive secondary coils, as shown in the drawings. The secondary coils 380 are in a closed oscillatory circuit 381, which includes a variable condenser 3.82, and which is arranged to control through an interrupter 383 a detector 384L019 any suitable construction, for instance, agaseous detector of well-known construction. A shunt circuit 385, controlled by aswitch 386, is shunted around the interrupter 383 to render the interrupter either effective or "non-effective at the will of the operator. The detector 384 is arranged to control a circuit387 containing a high potential battery 388, or other source of high potential current, and a telephone 7389, or other suitable receiving instrument or deyice. v V ,lVhen the system shown in Fig. 4: is used for receiving telegraphic messages, the switch 386, is kept closed and the interrupter 383 is arranged to be rotated at a uniform rate by a motor or any other suitable means not shown) to interrupt the circuit periodically at a frequency, for instance, of 1,000 'interruptionsper second,sotl1at when a signal'is being received by theopen circuit 350, an a'udible sound will be produced in the telephone'389.

For producing electrical beats in the two closed oscillatorycircuitsf369 and 369 controlling the secondary detectors 370 and 371, an electrical oscillator, including a thermionic valve 390 of any well-known or 'suijtable construction, is provided. This valve is arranged to contr01 a circuit including a battery'391 and a'coi l 392, which is in a closed oscillatory circuit 393, including ,'a variable condenser 394. This closed circuit 393 is adjusted so that a predetermined number of oscillations per second willbe setup 111 this closed circuit 393'as a result of the action of the valve .390. In

the present case, this closed circuit is adjusted or tuned to produce, under the action of the valve 390, continuous oscillations of a frequency either of 1,000 per second above, orv 1,000 per second belowthe second ary frequency of the system ;'in other words, to produce either 19,000 01 21,000 oscillations per second. The coil 392 is connected through a variable contact 395 andtwo variable condensers and 396 with the two closed circuits 369 and "369 respectively. By

this arrangement, oscillations having" a he quency eitherof 19,000 or 21,000 per second will be superimposed in the closed circuits 369 and 369 on the oscillations of 20,000 per second which are produced inthese'circuits by the action of the received waves, and consequently electr cal beats having a frequency of 1,000 per second will be produced in each of these two closed circuits 369 and 3 69. If the secondary oscillations of 20,000 per second in these two closed circuits 369 and 369 have a phase difference of 90, the

electrical beats 'set up as "just 'described in these circuits will also have a phase difl'erence of 90. p

In the operation of the receiving system shown in Fig. at, the oscillatory circuits 376 and 377 controlled by the secondary de- 300,000 and 250,000 oscillationspersecond and having imposed thereon 'periodicamplitude variations'of 20,000 'per second farere- 'ceived by the aerial circuit 350,'c0rrespon d ing oscillations are setup in the'closedcira cuits 358 'and'359, which act through the primary detectors 360 and 361 to set up oscillations having a secondary frequency of 20,000 per second in the closed circuits 366 and 367. These secondary oscillations produce corresponding oscillations, in the closed circuits 369 and 369 which control the two secondarydetectors 370 and-371. Elec- V trical beats of 1,000 per second are then caused to be set up in theclosed circuits 369 under the action ofthe thermionic valve 390. Thesebeats act through the secondary detectors 370 and 371 to produce electrical oscillations of substantially the same frequency of 1,000 per second andof substantially the same intensity in the two closed circuits 376 and 377,buthaving a phase difference of 90. The effect of these oscillations flOVV', ing through the two primary coils 373 and 37 1 will be to setup a 'magnetic'field which will remain substantially constant in strength but which will rotate uniformly, making one complete revolution for each beat cycle of the beat frequency.

"Electrical oscillations having the beattrequency willthus be set up in the closed circuit 381 containing the eight secondary coils 380, and these oscilliatlons will act through the interrupter 383 and through the final detector 384 to produce unidirectional impulses through the controlled circuit .387, 388 thifough the telephone or. other receiving instrument Through the action of the interrupter 383 these impulses will be in terrupted if desired to cause the telephone 389 to produce an audible sound or tone.

i, now, the operation of the transmission system should be modified so as to reduce the phase difference between the two series of amplitude variations to substantially zero, as by opening the switch 105 of Fig. 1, or the switch 261 of Fig. 2, then the magnet field produced by the primary coils 373 and 574 in the receiving system would cease to rotate, and consequently little, it any, current would be set up in the closed circuit 381, and the receiving instrument 389 would cease to operate.

l/Vhen the receiving system shown in Fig. 4 is used for receiving telephonic messages from a correspondingtransmission system, such, for instance,-as either of the transmission systems shown in Figs. 1 and 2, the switch 386 should be left closed to shortcircuit the interrupter 383 of. the receivin system, and the slight variations in the di ference in phase or the two series of periodic amplitude variations of the received waves due to the action of the telephone transmitter 115 in F ig, 1, or 265 in Fig. 2, would slightly vary the action of the primary coils 373 and 334 accordingly and cause corresponding variations in the oscillations in the closed circuit 381 and consequently corresponding variations in the current in the controlled circuit 337. These variations in the current in the controlled circuit 387 would cause the telephone receiver 389 to emit sound waves corresponding to the sound waves acting upon the telephone transmitter 115 in Fig. 1, or 265 in Fig. 2, of the transmission system. VJ hen used for telephony the beat frequency at the receiver is adjusted to a frequency substantially above audibility, for instance, to 10,- 000 cycles per second, instead 01: 1,000 cycles per second.

In Fig. 5 is shown a further modified form of ransmission system constructed in accordance with this invention. This modified form comprises two open aerial circuits 400 and 401, which include respectively an antenna 402 grounded as at 403 through a coil 404 and an alternator 405, and an an tenna 406 grounded as at 407 through a coil 408 and an alternator 409. These two open circuits 400 and 401 are tuned respectively to two different frequencies, for instance, to 200,000 and 100,000 oscillations per second, and the two alternators 405 ant 409 are arranged to generate alternating current of the same frequencies respectively as the frequencies to which the open aerial circuits 400 and 401 are tuned.

For in'iprcssing'periodic amplitude variations of the same frequency and either of the same phase or difierent in phase upon the high frequency oscillations set up in the two open circuits 400 and 401 by the alternators 405 and 409, the two coils and 403 are arranged to surround respectively two corresponding sides of two soi't iron rectangular cores 415 and 416, which are arranged to be magnetized respectively by two magnetizing circuits 417 and 413, which include respectively two coils 419 and 420, two batteries 421 and 422, and two rheostats or variable resistances 423 and 424, the coils 410 ant being arranged to surround two corresponding sides oi the two cores 415 and 416. A third side of each of the cores 415 and 416 is surrounded by a coil 425, and these two coils 425 are respec tively in two intermediate circuits 426 and 427 including respectively a variable inductance 423 and a secondary coil 429, and a variable condenser 430 and a secondary coil 431. Arranged between the secondary coils 429 and 431 is an auxiliary circuit 435 including two primary coils 436 and 437, and an alternator 440, which is arranged to set up alternating current having the same trequency as the frequency of the periodic an'iplitude variations which it is desired to impress upon the oscillations in the open aerial circuits 400 and 401, for instance, having a frequency 01 20,000 alternations per second. The primary coils 430 and 43" are inductively coupled to the secondary coils 429 and 431 in such a manner that when oscillations are set up in the closed auxiliary circuit 435 by the alternator 440 COIIQSPOIlCilDg oscillations will be inductively set up in the two intermediate circuits and 427 and will act upon the two cores 415 and 416 to periodically vary the free magnetization of the two coils 415 and 416 and consequently to periodically vary the inductant effects or the two coils 404 and 408 and throw the open aerial circuits 4.00 and 401 into and out of tune at the frequency of the alternator 440 oi the auxiliary circuit 435, thus periodic lly varying the amplitude of the electro-radiant oscil lations emitted by the open circuits 400 and 401 at the same rate, for in tance, of 10,000 per second.

For varying the phase relationship in the periodic amplitude variations of the two series of oscillations emitted by the open aerial circuits 400 and 401, a variable condenser 441 is in a circuit 442 shunted around the variable condenser 430 and controlled by a key or switch 443. These variable condensers 430 and 441 are preferably so adjust-ed that when the key is closed and the system is in operation, a phase difference of approximately 90 will be produced between the two series of periodic amplitude variations of the emitted waves, and when the key 443 is open, this phase difference will be reduced to :so that the two series of periodic amplitude variations will be in the same phase.

For adapting the system shown in Fig. for use in transmitting telephone mes sages, a telephone transmitter or microphone and 100,000 oscillations per second.

445 is arranged in a circuit. 446 shunted around the key 443 and controlled by a switch 447. When it is desired to use the system for transmitting telegraphic messages, the switch 447 is left open and the key 443 is used for transmitting the messages, but when it is desired to use the system for transmitting telephone messages, the key 443 is left open and the switch 447 is kept closed.

The transmission system shown in Fig. 5 may be utilized in connection with a receiving system such as is shown in Fig. 4, or any other suitable receiving system, to transmit either telegraphic or telephonic messages, and when so used will cause the operation of a receiving device as a result of a difference in phase between the two series of periodic amplitude variations, as hereinbefore described.

In Fig. 6 is shown a modified form of transmission system constructed in accordance with this invention and arranged to emit three series of high frequency oscillations having three different frequencies re spectively, and provided with means for impressing upon the three series of oscillations three series of periodic amplitude variations having the same frequency, and

.means for varying the phase relation between the three series of periodic amplitude variations.

This modified system shown in Fig. 6 comprises three open aerial circuits 460, 461 and 462, each of which comprises an antenna 465 grounded as at 466 through a coil 467 and a high frequency alternator 468. These three open circuits 460, 461 and 462 are tuned respectively to three different frequencies, for instance, to 200,000, 150,000 The three alternators 468 are arranged to gen erate electrical alternations having the same frequencies respectively as the frequencies to which the open aerial circuits 460, 461 and 462 are tuned.

F or impressing three series of periodic amplitude variations upon the threeseries of oscillations set up in the three open circuits 460, 461 and 462, the three coils 467 surround respectively three corresponding sides of three magnetic soft iron cores 470, which are arranged to be magnetized by three batteries 471 acting through three rheostats'472 and three coils 473 which surround respectively three corresponding sides of the three cores 470. F or periodically varying the magnetization of the cores 470,

a'three-phase high frequency alternator 475 is arranged to deliver energy to a threephase'transformer 476 which includes three primary coils v477. Theseprimary coils 477 are inductively coupled respectively to three secondary coils 478, which are respectively in "three intermediate circuits 479, including resp'ectively three coils 480 which surround corresponding sides of the cores 470 respectively. Two of these intermediate circuits 479 include respectively a variable inductance 481 and a variable condenser 482. Thevariable inductance 481 and the variable condenser- 482 may be so adjusted that the three series of periodic amplitude variations set up in a uniform rate by any suitable means (not shown). The surface of'this commutator is divided longitudinally into twospaced portions insulated from each other by a cylindrical strip 490 extending centrally around the commutator. The four brushes-are ar ranged to engage the surface of the commutator along a line which is parallel with the axis of rotation of the commutator,,and are arranged in pairs 486, 487 and 488, 489 to engage the two spaced'portions of the commutator respectively. Cylindrical surfaces of the two spaced portions of the commutator are made up respectively of two aligned series of equal conducting segments separated by two aligned series-of equal insulating segments. These segments are so "arranged thatas the commutator rotates each aligned pair of conducting segments are moved simultaneously into and simultaneously out of engagement with thepairs of brushes 486, 487 and 488, 489 respectively. 7

One pair 486 and 487 of the brushes are connected respectively by conductors 491 and 492 toone side of the variable inductance 481 and to a key or switch 498, which is arranged to swing about a fixed axis and tobe moved into and out of engagement with three aligned spaced contacts494, 495 and 496 fixed in the path of the key. The key 498 comprises two conducting portions which are separated by an insulating portion 497, andthe arrangement of the insulated portion is such-that when the key 493 is closed upon the contacts 494, 495 and 496, the key will electrically connectthe contact 494 with the conductor 492, and the contact.

495 with the contact 496, but will not electrically connect the contact 494 with the contact 495. The other pair of brushes 488 and 489 are connected respectively by two conductors 498 and 499 to. the fixed contact 496 and to one side of the variable condenser 482. The other sides of the variable in" ductance 481 and the variable condenser 482 are connected respectively by conductors 500 and 501 to the fixed contacts 494, and 495.

In the operation of the transmission system shown in Fig. 6 for transmitting telegraphic messages, the commutator 485 is caused to rotate at such a rate as to cause the circuits controlled by the brushes 486 to 489 to be interrupted at a rate of, for instance, 1,000 interruptions per second, and the key 493 is used to send the telegraphic signal. As long as the key 493 is open, the variable inductance 481 and the variable condenser 482 will be included in their corresponding intermediate circuits 47 9 and will act upon these circuits to cause thethree series of periodic amplitude variations to be impressed upon the open aerial circuits 460, 461 and 462 simultaneously and in the same phase, but when the key 493 is closed, the variable inductance 481 and the variable condenser 482 will. be simultaneously and periodically short-circuited automatically at a rate controlled by the commutator 485, for instance, at. a rate of 1,000 per second, and each time that these elements are short-circuited the phaserelation between the three series of periodic amplitudevariations will be modified in such a manner as to produce a diil'erence inphase of 120 between the periodic amplitude variations of one'series and the periodic amplitude variations of the,

second series, and also a phase difference of 120 between the periodic amplitude variations of the second series and the periodic amplitude variations of the third series.

in the operation of the transmission systemshown in idig. 6 for transmitting telephonic messages, the commutator 485 is caused to rotate at a frequency above audibility but lower than the secondary frequency of the system which is produced by high frequency alternator 475, and the two switches 493 and 514 are both kept closed. The telephone message may then be transmitted by speaking into the telephone trans mitter 511. r i

In Fig. 7 is shown a receiving system constructed in accordance with this invention and arranged to receive either telegraphic r telephonic n'iessages transmitted by the transmission system shown in Fig. 6, or by any other suitable transmission This receiving system includes three open aerial circuits'525 which are tuned respectively to the three'difi'erent frequencies of the waves intended to be received, for instance, to 200,000, 150,000, and 100,000 oscillations per second. These three open circuits 525' are inductively coupled to three closed oscillatory circuits 526. which are correspondingly tuned to the same frequencies respectively as the open circuits; These closed circuits 526 are arranged in a well known manner to control respectively three system..

primary detectors 526 of any Well-known or suitable torm, the detectors shown being gaseous detectors of well-known form. These primary detectors 527 are arranged to control respectively three circuits 528 including respectively three primary coils 529 and three high potential batteries 530, or other suitable sources of electric energy. The three primary coils 529 are arranged respectively in three closed oscillatory circuits 531, including respectively three variable condensers 532. These circuits 531 are each tuned to the secondary.frcquencyof the transmission system, for instance, to 20,000 oscillations per second. The three primary coils 529 are inductively coupled respectively to three secondary coils 535, which are respectively in three closed oscillatory circuits,

536, 53,7 and 538, which include respectively three variable condensers 539, and three primary coils 54 541 and 542.. These three closed circuits 536. 587 and 538are each tuned to the secondary frequency otthe tem, for instance, to 20,000 oscillations per second. The primary coils 540, 541 and 542 are each divided into two spaced aligned sections and are so arrangedthat their longitudinal axes lie in the same plane and in terscct ata common point about which these axes are equi-angularly spaced. Surrounded by the sections of the three primary coils 540, 541 and 542 are six secondary coils 545, which are arranged so that their longitudinal axes are in a plane with the longitudinal axes of the primary coils and radiate equi-angularly from the point of intersection of the longitudinal axes of the primary coils. The secondary coils 545 are also arranged so that the longitudinal axes of each pairot' opposed coiis coincides witha line which biclosed circuit 546 is arranged to control a secondary gaseous detector 548 of welh known construction. This secondary dete tor is arranged to control a circuit 549 including a high potential battery 550' and a primary coil 552. The primary coil 552 is in a closed circuit 553, which includes a variable condenser 554 and which is tuned to the thirdfrequency oi the system the third frequency being predetermined by the commutator 485 of the transmission system shown in Fig. '6 and being,ior instance, 1,000 oscillations per second. The primary coil is inductively connected to a secondary coil 555 which is in a closed circuit 556, including a variable condenser 55?, and

which is tuned to the same frequency as the closed circuit 553. V The closed circuit 556 is arranged to control an auxiliary detector 558,'which in turn is arranged to control a circuit 559, including a high potential battery 560 and a telephone 561, or other suit able receiving device.

In the operation of the receiving system shown in Fig. 7, when three series of waves from the three transmitting systems shown in Fig. 6 are received by the three open circuits 525,'three series of oscillations oi' a frequency of 20,000 per second will be set up respectively in the three closed circuits 536, 537 and 538 under the control of thethrec primary detectors 527. ,These three series of oscillations will have a phase difference substantially of 120, which is varied to approximately zero periodically at a rate of 1,000 variations per second through the action of the commutator s85 01 the transmission system shown in Fig. 6, and consequently these oscillations will act in the primary coils 54:0, 54:1'and 54-2 to set up a magnetic field around these coils which will alternately rotate at a rate of 20,000 revolu tions per second, and remain stationary at the rate of 1,000 times per second, and the effect of this magneticfield upon the secondary coils 54.5 will be to setup an oscillating currentof 20,000 oscillations per second in the closed oscillatory circuit 5 16 containing these secondary coils, and the amplitude or these oscillations will be varied periodically at'the rate 01": 1,000 variations per second owing to the interruptions of 1,000 per second in the rotary movement oi? the magnetic field. act through the secondary detector 548 to set up current'impulses of 120,000 per sec 0nd, periodically'varied in amplitude at the rate of 1,000 variations per second, in the j circuit 549 controlled by the secondary de- .duced in the telephone receiver 561.

tector. set up oscillations of 1,000 per second in-the closed circuit 553 which will act to set up corresponding oscillations in the closed. circuit 556, which in turn will act through the auxiliary detector 558 to cause unidirectionalimpulses hav ng'a frequency of 1,000 per second to fiow through the circuit 559 conand pro-

trolled by the auxiliary detector 558, consequently an audible tone will be 7 In Fig. 8 is shown an improved transmission system coiistructed in accordance with ternator 579. These four open circuits 570 to 573 are tuned respectively to four different frequencies, forinstance, to 200,000,

160,000, 120,000 and 100,000 oscillations per second, and the corresponding four alterna- V tors 579 are arranged to generate alterna- These oscillations will These impulses thus modifiedwill tions of the same frequencies respectively as the frequencies to which the open circuit-s 570 to 573 are tuned. I

For impressing periodic amplitude variations upon the four open circuits 570 to 573, four rectangular soft iron cores 580 are arranged to extend through the tour coils 578 respectively. These cores are-arranged to be magnetized to a suitable degree respectively by four batteries 581 acting re spectively through four rhecstats 582 and four magnetizing coils 583, which are wound around the respective cores; For impressing upon two of the open circuits 570 and 571 amplitude vaii'iationshaving one irequency, for instance, of 20,000 per second, and for impressing upon the other pail-of open circuits 572 and 573 periodic amplitude variations having a different frequency of, for instance,21,000 per second, two electric alternators. 585 and 586 are provided. arranged to generate alternations of 20, 000 per second and 21,000 per second respectively in two closed circuits 587 and 588, each of? which contains two primary coils 589 and 590, and 591 and 592. The primary coils 589 and 590 are inductively connected to the secondary coils 593 and 59a,

denser 600, The two primary coils 591 and I 592 are inductively connected to two; sec

ondary coils 605 and 606, which are in two intermediate closed circuits 607 and 608,

which include respectively two coils 609 and 610, which surround respectively correspond-- ing portions of the two cores 580 of the two open circuits572and 573. These two intermediate circuits 607 and 008 con tain respectively a variable condenser 611 and a variable inductance 612. For short contacts 6141, two of which are connected respectively by two conductors 615 to the o posite sides ofone of thevariaole condenserg 600, and the other two or which are con nected respectively'bya conductor 616 to the opposite sides of the other variable condenser 611. llhen the he 61.3 is closed,

the two variable condensers 600 and 611 will be short-circuited; When the key open, the twocondensers 600 and'fill will shift the phase of the two intermediate cir cuit-s 596 and 607.

In the operation of the transmission sys tcm shown in 8, the two variable condensers'600 and 611 are so adjusted that circuiting the two variable condensers 600" and 611, a switch 613 is arranged to swung into and out of ei'igagement with four fixed when the alternators 579, 585 and 586 are in operation and the key 613 is open, four series of continuous oscillations having" wave frequencies of 200,000, 160,000, 120,000 and 100,000 respectively willbe emitted by the tour open circuits 5T0 to 5T3, and upon the two series of oscillations en'iitted by the two open circuits 570 and 571 will be impressed respectively two series of periodic amplitude variations having the same frequency or 20,000 per second and diii'crinp; in phase by 30, while upon the two series of waves emitted by the two other open circuits 572 and will be impressed respectively two series of peri dic an'iplitude variations having; the saine'trequency of 21,000 per second but di-tlering'in phase by 00. Now it the key 618' should be closed, the two variable condensers 600 and 611 will be short-circuited and the tour open circuits 570 to 573 will continue to emit tour series of waves periodically aried in amplitude, as just described, but with substantially no difference in phase between the two series of periodic amplitude variations impressed upon the waves emitted by the tour open circuits 57 0 to 573, or by the two open circuits 572 and To adapt the transmission system shown in Fig. 8 to be used for sending either telegraphic or telephonic messages, a double telephone transmitter 61" is provided, which is of well-known construction, including a mouthpiece 618 and two microphones 619 controlled by the mouthpiece 618. These two microphones 619 are connected through two pairs of conductors 620 and 621 to the two pairs oi conductors 615 and 616 respectively, and the telephone transmitter 617 is provided with a switch 622 whereby the transinitter may be thrown into or out of operation. YVhen it is desired to use the system for transmitting telephone messages, the speed oi? one of the alternators 586 is increased to, for instance, 30,000 alternations per second so as to produce a difference oi 10,000 or more alternations per second between the two secondary frequencies of the system. '1? he liey 613 is now" opened the switch 622 is closed to throw thetelephone ransmitter 61? into operation. The variable condcnsers 600 and 601 are then adjusted so that when no sound waves are being directed into the mouthpiece 618, there will. be a phase ditlerenee oi" snbstantially 00 between the two series of amplitude variations mpressed upon each pair ot series of en'iit- Now when the operator ed oscillations.

L speaks into the mouthpiece 618, the resis= tances of the two short circuits around the two variable condensers 601 and 601 will be simultaneously varied in accoruance'with the sound waves received by the nioutlr 1 iece 618, and in consequence the phasedi once of between each pair oit' series of amplitude variations will be accordingly inodified and will affect the receiving system accordingly, as will appear hereinafter.

In Fig. 9 is shown a receiving system con-- structed in accordance with this invention and arranged to receive tour series of waves transmitted by a suitable transmission system as for instance, the tran shown in Fig. 6, and h inbe scribed. This receiving system shown in Fig. 0 comprises four open aerial circuits 625, 626, 627 and 626, which are timed respectively to the tour different high frequencies of the received wares, tor instance, gto 200,000, 160,000, 120,000 and 100,000 oscillations per second. The tour open aerial circuit-s 625 to 628 are inductively connected res ectively to four closed oscillatory circuits 630, which are tuned respectively to the same trequenciis as the frequencies of the open circuits 625 to 628. These tour closed circuits 630 are arranged to control tour primary detectors 631, of suitable construction, but which in the form shown are gaseous detectors ct well-known construction. These four detectors 631 control retour closedcircuits 632, 633, 684, and 635, which include respectively four high potential batteries 636 and tour primary coils 637, 638, 639 and 640. lhese primary coils 637 to 64-0 are arranged so that their longitudinal axes are equi-angularly arranged around a point, and so that the longitudinal axes of the two coils 637 and 638, controlled by the pair or" open circuits and'626, will intersect at right angles, and so that the other pair of primary coils 639 and 64:0, controlled by the other pair of open circuits 627 and 628, will also intersect at right angles. Eachof these primary coils is formed in two spaced aligned sections, thus allowing the insertion of a group oil secondary coils 650 into the fields of these primary coils; These prin'iary coils 63? to 6-10 are arranged respectively in tour oscillatory circuits 6 11, 6&2, 6933 and 66%, which include re ectively tour variable c ndensers 646,646, 6 17 and 648. The two closed circuits d 642, con- 6 l1 air tair g; respectively the two primary coils 63*? and 668, are each tuned to the same one of the two secondary frequencies of the rereived waves, for instance, to 20,000 oscil lotions per second, while the closed circuits 6e?) and 6%, containing the primary coils 630 and 64.0., are each tuned to the other secondary frequency oi? the received waves, for instance, to 21,000 oscillations per second. gurrounded by the eight sections the {our primary coils 667 to 640 are number, eight, of secondary coils 650, which arrange-" so that their lonidinal lie one with the loniudinal es o the primary coils 637 to and r2 ate troin and are equrangularly disposed around the point of intersection 

